Traps in plumbing are devices to contain sewer gas from rising from a municipal or septic tank sewage system up into a plumbed building via the drain hole on washing vessels. Usually gas ingress is halted by the trapping of a quantity of water between a vessel drain and a sewage system, although rubber seal hinged and sprung hatches are also used in less developed nations. Trap systems consist of the vessel they are connected to, as well as the drain fitting connecting a vessel fixture to a drainage pipe, as well as the sealing connecting assemblies that connect the drainage pipe to a trap fitting, and finally a waste arm leading to a vented vertical drainage pipe or “stack” connecting and draining many fixtures. The vessel of interest in this Application is called a lavatory or sink or even lavatory sink, all three names referring to a hand-washing sink. The lavatory sink is secured to a wall or counter and equipped with pressurized supply water fittings terminating in a faucet or faucets that supply water to the lavatory interior. The environment of interest in this Application is the infection control environment, for example, hospitals. The first line of infection management in infection control is the elimination, where possible, of uncleanable niches for microbes. Accordingly, internal overflow channels found in older household bathroom sinks are contraindicated for infection control environments, owing to restricted access for cleaning of the overflow channel. Consequently, overflow channels will not be addressed in this Application. The fixture fitting attached to the bottommost hole draining the vessel is called the drain or lavatory drain, and to the bottommost extremity of said drain is connected a tailpiece constructed of tubular metal or plastic and connecting to a downstream trap. In some installations accommodating wheelchairs under the lavatory, the tailpiece may be replaced by an elbow connected to a horizontal tube of metal or plastic connected eventually to a downstream trap. In either case, downstream of the trap is a horizontal waste arm comprised of tubular plastic or metal leading to the larger drainage system. Trap design has evolved greatly in order to achieve two objectives. The first objective is the containment of sewer gases over the service life of the trap. The second is to be cleanable. Current to the date of this Application, most traps in North America are required by building codes to be a tubular trap constructed of tubular plastic or metal bent into form and connected with various connection and sealing assemblies. Colloquially, a tubular trap assembly made of tubular metal or plastic connected to a lavatory is called a “P-trap” owing to its similarity in shape to the letter p in a horizontal position. The portion of the tube bent 180 degrees is referred to as the “J-bend” owing to one arm of this part being higher than the other. Critical in the J-bend is the air gap between the two upward tubular arms of the bended part, and the height of said gap. In contrast, a trap part comprising tube bend 180 degrees at the tube midpoint to form two upward arms of equal length would be called a “U-bend”. Other manufacturing methods of the U-tube, such as casting, moulding, and forging may be preferable or necessary.
In this Invention called the removable trap for lavatory sinks, the traditional trap fitting system is modified to maintain said sewer gas control while enabling the provision of a removable tubular water trap portion for thorough cleaning or replacement. Easy removal of said trap portion has hitherto been impossible if the first functional objective of reliable sewer gas containment were to be maintained. The Invention described in this Application is able to meet both said objectives.
Through the provision of said objective of containing sewer gases and provision of said objective of cleanability through replaceability of the tubular trap part of the trap, the Invention described in this Application can be used as a tool to manage infectious microorganisms in an infection control environment. Lavatories are principally used for hand washing. Repeated use to wash hands, as well as the introduction of other biological refuse, can lead to build up of biofilm plaques containing infectious bacteria in the nutrient rich water trapped within the trap fitting. Biofilms are complex adhering structures produced by bacteria that enable differentiation in bacterial functionalities. Said bacteria can splash back up into the sink interior and be vectored onto human hands and other surrounding items, promoting infection where infection would not have occurred without the lavatory. This leads to the ironic situation in that the device, said lavatory, placed at great expense through the hospital to enable medical hygiene through hand-washing, poses the greatest risk of any hospital equipment. The Invention in this Application enables not only thorough cleaning, but elaboration of materials and processes centering around the tubular trap tube cartridge portion only, to concentrate expense on the retaining portion of the trap, said J-bend described earlier. Not only is the trap the origin of most infectious microorganism risk, it is also the portion of the trap system most vulnerable to attack by strong cleaning chemicals used in infection control environments such as hospitals. Rather than sacrificing anti-microbial properties of the trap material for the longevity perceived to be of importance in commercial buildings, the trap J-bend can be viewed as a replaceable item maximized for infection control. In practice, most hospital maintenance staff have anticipated this Invention by the awkward process of periodically replacing the entire trap assembly, a costly and time consuming exercise. The Invention described in this Application will provide an easier way to replace the most important, the most vulnerable, and the most powerful locus of infection management technologies. This strategy is common to medical hygiene, where disposable parts, for example the disposable plastic shroud on an electronic thermometer, are key in infection management. It is time this most Victorian of fittings, the lavatory trap, be adjusted to meet the expectations of modern infection control.
The history of modern trap starts largely with Thomas Crapper in England, who found that vectoring toilet waste with flush water into a tank pit equipped with an overflow prevented the ingress of sewer gas into the household. However, said pit traps posed a cleaning nightmare. Modern interpretations of Crapper's trap to the lavatory sink have generated a variety of patent applications, each illustrating important aspects of trap design. As a sample, Nunez (U.S. Pat. Appln. No. US 2004/0177439, Sep. 16, 2004) provides instead of a P-trap, an egg-shaped receptacle accepting the drainpiece from above and equipped with a waste arm to the side. If the bottom of said tailpiece is inserted such that its bottom end lies below the lowest point of the diameter of the exit port to the waste arm (commonly this lowest exit point downstream to the trap is called the “weir”), Nunez considered that this would be a sufficient barrier to trap gases as well as easy to clean. North American plumbing codes have all rejected this style of trap, called the “bottle trap” owing to its superficial resemblance to a beer bottle, for two reasons. One rejection reason is that siphonage can occur more easily without at least two inches of trap height to the weir. If water is siphoned out of the trap, this can lead to an empty trap, defeating its very purpose. More importantly, it is impossible to visually assess whether the tailpiece from the drain is below the weir by looking at the exterior of the trap. What happens often is that a long tailpiece extended even 2″ below a weir will develop perforations above the weir. In this case, gases short circuit the trap, again defeating its very purpose. Bacon (U.S. Pat. Appln. No. US 2009/0308463, Dec. 17, 2009) presents another bottle trap that does indeed have an integral barrier inside to preserve the two inch to weir trap height that resists siphoning. However, there is no way to visually assess that that barrier is not perforated without disassembling it, and even then assessment of the integrity of the integral barrier would be difficult. Bottle traps have therefore been expressedly defined and banned in all building codes in Canada and the United States. Instead, the P-trap is preferred. If one or both walls bounding the gap in the J-bend fail, the trap will leak to the ground, an easy visual test. Further, the gap can be sized to preserve a 2″ weir height on the inside of the J-bend to resist siphonage.
The trapping of sewer gases has been stated to be one objective of trap design. The other was cleanability. Ana (U.S. Pat. Appln. No. US 2006/0265804, Nov. 30, 2006) accepts the J-bend and attempts to add a cleanout consisting of a threaded plug and port. The novelty of Ana's application is that the cleanout port is horizontal, provided on the side of the J-bend to more easily accept a cleaning brush. Usually if a threaded clean-out port is provided, it is found on the lowest point of the J-bend. In either case, these tiny cleanout ports are unusable in infection control environments for a variety of reasons, including the unsuitability of any design of brush for cleaning tubes lined with biofilms, and more simply the leaking or corroding of said cleanouts. Beaumont (U.S. Pat. Appln. No. US/2014/0000019, Jan. 2, 2014) present an example of a brushless but high risk cleaning device consisting of a tube connected at the upstream end to water supply, and at the bottom end resting freely in the trap. Independent of its functionality, if the water supply pressure goes negative, as periodically happens, the trap water with its high risk of infectiousness would be directly sucked up into the fresh water supply, with potentially disastrous complications once supply water pressure returns. Any device not equipped with an air gap or other backflow prevention device is strictly illegal. This sort of direct flush can be designed in many ways, all of them strictly forbidden by building codes in Canada and the United States owing to said risk of cross-contamination of potable supply water with infections drainage water. The conclusion from a limited library of trap design applications is that the easiest and safest way to clean a trap is to design a trap that enables the easy and periodic removal of the water-containing 180 degree bend portion of the J-bend. Such a system is described in this application.
The removability of a trap enables other tools in fighting infection spread other than regular cleaning enabled by easy replaceability. These tools include enabling concentration of expense of material and methods into the portion of the trap most likely to support biofilm growth. Construction of the U-bend portion out of material that is inherently anti-microbial, for example certain copper alloys, or coated to be anti-microbial, is less expensive for hospitals when only the removable portion receives this special treatment. Processes such as heating can be incorporated just into the U-tube, and improvements made without discarding the entire trap assembly.
In conclusion, the U-tube portion of the lavatory trap system can be constructed of a plurality of plastics, metals, and other materials, using a plurality and possible combination of bending, soldering, welding, injection moulding, die-casting, forging, and other manufacturing methods. The ability to modify just the U-tube allows for easy cleaning, regular replacement, provision of purposeful materials, provision of purposeful technologies all to achieve antimicrobial ends and manage risk of infectiousness.